Prostate Cancer High Dose Rate (HDR) Brachytherapy
1 Scope
This document describes the medical/surgical technique aspects of prostate HDR brachytherapy. The description is a guideline, since these operative procedures are by their nature individualized. In addition, this guideline should be used in the context of multiple other documents listed below, describing selection of patients for HDR brachytherapy, the preadmission procedures, the planning procedures including prescription doses and suggested constraints, the actual treatment procedures and an Alfred Hospital “Clinical Pathways” protocol describing their inpatient care.
2 Responsibility
Head Brachytherapy Services
3 Other Relevant Documentation
Alfred Temporary Prostate Needle Brachytherapy Clinical pathway
WBRC Prostate Cancer Treatment Guidelines
WBRC Prostate HDR Patient-held medical record
WBRC HDR CT scan procedures
WBRC HDR prostate brachytherapy planning policy and procedures
Operating suite HDR brachy instrumentation and patient setup check list
Alfred Anaesthetics department oral analgesia for prostate HDR policy memo
3.1 Introduction Preoperative Preparation
Patients who have an HDR brachytherapy implant will have been evaluated, advised and counselled in WBRC outpatient clinics by Radiation Oncology Specialists regarding the need for HDR brachytherapy. The patients will have generally been seen and assessed at a “preadmission” clinic as described in the “Clinical pathways” with preoperative physical evaluation, investigations, and documentation of in-patient and discharge medications. They will have been also counseled by the MPI nurse, and given the “Patient Held Clinical Record”, containing detailed information about the procedure, the possible side-effects, and instructions about preparation for the operating theatre. “Billing status” should have been discussed and documented. A consent form for brachytherapy radiation treatment, and a consent form for the surgical procedure must be properly completed and signed before the implant can proceed. The patients will have been on a low residue diet as detailed in the “Patient-held Clinical Record”.
Patients generally will come straight to the Alfred Centre Operating Room from the patient reception area, after an enema and with TED stockings applied, as described in the clinical pathways The procedures are generally booked for the first implant to begin at 8.30am, which implies the anaesthetic preparation should begin at 8.15-8.20am. This means that WBRC staff must also be ready on time, with the Radiation Oncologist on the Operating suite floor no later than 8.10am 00am (for a 8.30 start) to speak with the patient in the reception area prior to him going into the operating room.
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3.2 Anaesthetic care
The Alfred Hospital anaesthetic department is responsible for the anaesthetic care of our patients, and we work in cooperation with them in achieving optimum postoperative pain-relief as described in the clinical pathways and in the anaesthetics department document on oral analgesia recommendations.
We prefer spinal anaesthetics for these procedures and this should be the “default” anaesthetic technique employed. However, the anaesthetist is finally responsible for determining this after his or her discussion with, and evaluation of, the patient.
The patients should be given antibiotics (generally metronidazole and gentamicin) and anti-thrombotic prophylaxis (generally clexane) as detailed in the clinical pathway.
3.3 Patient setup
The operative equipment, instruments, and patient draping and preparation are described in the operating room HDR checklist. Briefly, the patient is placed in the dorsal lithotomy position, with his legs in “Yellow-fin”® or similar stirrups. A “urology table” should be employed. The patient is positioned so that the anal verge is at the end of – or slightly over – the end of the table. The stirrups are elevated so that the thighs are slightly hyperflexed (that is, slightly past vertical), in order to gain the maximum room under the “pubic arch”. The patient must be carefully positioned straight on and centred on the operative bed. The legs are elevated; check his knees are flexed equally from looking from the lateral aspect, and check the knees are at the same height (a spirit level can assist with this). This will generally set the prostate up correctly, but many men have slightly asymmetrical hip thigh or pelvis anatomy so check the anal canal, and make fine adjustments as needed. A digital rectal exam should be performed to check on bowel prep, to expel any residual content, and to check and allow documentation of the palpable features of the prostate.
The surgeon scrubs and gowns in the standard fashion, preps the perineum, genitals, medial thighs, lower anterior abdominal wall, anus, and buttocks with skin prep. The patient’s legs, and abdomen are draped in the standard fashion.
A three-way Foley catheter is placed in the standard fashion, the bladder drained, and 120 ml mixed saline and radiographic contrast injected into the bladder. The catheter balloon is half inflated with water and some air (sufficient to keep the catheter in the bladder, but not so the balloon is “tense”, and so less likely to be ruptured by a catheter in the bladder). The catheter is spigotted.
The scrotum, penis, and pubic area are dried with a dry pack, and then a folded dressing placed over the genitals and scrotum and a large piece of sterile Opsite® film placed over that, positioning the caudal edge of the film above the upper (anterior) end of the perineal field, and sticking it down over the genitals and perineum, up to the anterior abdominal wall, to hold the genitals out of the way.
A “C-arm” fluoroscopy machine with sterile cover is positioned to enable visualisation of the pelvis, perineum, and bladder
3.4 Implant setup
These instructions refer to the use of the BK Pro-Focus® Ultrasound machine and biplanar electronic probe, and the Microtouch stepper and stabilizer but the principles hold for other systems.
Preparation. The ultrasound probe and water-balloon stand-off cover is prepared by an RT using a clean technique. The ultra-sound probe should be free of air bubbles in the water stand-off cover. The probe is attached to the stabiliser and stepper. It is a useful practise to position the adjustable metal position marker on the Microtouch stabilizer near the middle of the movement range, at about “4535”. This will mean, if these instructions are followed, that the TRUS movement range will be optimised for the implant because it will result in having a wide range of movement above the base of the prostate, which is where it might be useful or necessary. Check that the fine adjustment setting of the probe allows more movement of the probe in the posterior direction than in the anterior direction, because this directional adjustment is more likely to be needed. Similarly, make sure there is equal movement available left and right.
Insertion. The lubricated probe is inserted into the anal canal, and positioned. Generally this means the long axis of the probe is parallel with the long cranial-caudal axis of the prostate. The image should be set to an axial view. Inject 10 ml or so of water into the balloon stand-off cover. Quickly preview the imaged anatomy to orientate yourself and ensure there will be no unexpected findings later during the procedure. Identify the prostate from apex to base, note the catheter in the urethra and the general “trajectory” of the urethra, note any anomalies or variants in the rectal wall, Denonvilliers fascia or prostate (such as cysts), check the seminal vesicles and the bladder, check if there is a median lobe, and finally look at the prostate base.
Alignment. Optimise the probe angle. At steeper angles pointing down the catheters will be further from the anal sphincter at and below the prostate apex and there will less loss of contact and poor imaging in the apical axial planes, but a higher risk of pubic arch interference. The probe tip (axial transducer) should be positioned so that (for HDR implants) the “D” row (on the electronic grid created over the BK® monitor image) bisects the left-right dimension of the gland at about mid-gland level. This will be near the axial section of greatest right-left width. Try to align the urethra in the “D” plane. This might mean the prostate is not centred, if the urethra in the particular patient is not on the mid-sagittal plane. Simultaneously, check the prostate is not rotated; that is, the posterior wall of the gland is parallel with the numbered rows of the electronic grid. In the case of HDR implants, the gland will generally be “pulled” forward in the anterior direction so that it is worth starting with the posterior border of the prostate well below the “1” row of the BK® template grid system. Adjust the stabilizer system until this alignment is achieved, then “lock” the stabilizer and stepper position.
Movement and measurements. Before proceeding, check the Ultrasound ultrasound image is optimised. Check the focal plane (at about 2cm), frequency (usually ~5MHz), and the image size. Optimise the gain control. Check through the extreme range of probe movement to view axial planes from above the prostate (check the bladder, and the position of the catheter balloon), through the prostate noting again the course of the urethra (generally it will lie between “c” and “d”, and between “2” and “3.5”) and the apex. It is useful to note the height, width and length of the prostate at this point, to guide later volume marking on CT. Make sure there is no artefact degrading the image at one of the planes. The implant can now proceed.
3.5 Catheter implant
3.5.1 “Stabilising” catheters.
The initial aim is to use two catheters to “stabilise” the prostate gland. The prostate is relatively mobile and tends to rotate away from any individual needle as it penetrates through the gland. As the procedure progresses this becomes less of a problem, because the increasing number of needles tends to “transfix” the gland. Initially however, it can be a problem and it is mitigated by using initial needles that penetrate the gland near its middle.
There are (at least) two methods for catheter placement. The Nucletron flexible plastic catheters are sharp, but not as sharp as steel needles. They can be used on their own to penetrate skin (and prostate), but need a bit of force and a strong grip. The best technique for these is to puncture through the skin first, which is the toughest part, with a short sharp quick penetrating jab. The catheter can then be progressively pushed through prostate. There is a distinctive popping sensation when the needle penetrates through to the bladder.
The other method of placement is to use sharp steel needles initially. A steel needle can be used to puncture the skin (and maybe form a track in the prostate). These are then removed, and the sharp-tipped plastic catheter is then placed in the prostate through the track formed by the first needle. This technique is repeated for each catheter.
Start with the axial US image of the axial plane at about the midprostate level (about 2 cm caudal to the prostate base). Use two Nucletron™ catheters, one on the left and one in the right, in about the midgland from anterior to posterior (so lying on about the same numbered row as the urethra in that midgland probe image). Place them at approximately the C and E row, so they are about equidistant from the lateral prostate capsule and the median urethra. Push them through the skin, and then simultaneously push them smoothly into the prostate, towards the prostate base. Check the catheter positions on axial TRUS image. Often the gland will be pulled anterior. Reposition as necessary. Now rotate the probe with in its holder, in the stepper, so one of the catheters now lies in the D row of the TRUS grid. Switch to the sagittal planetransducer on the TRUS probe, and step the probe further into the anal canal. The catheter to which you rotated the probe transducer plane will come into view, in a sagittal image. Identify the distal sharp tip, and advance this catheter through the base of the prostate, and into the bladder. At this point, obtain an image of the catheter on the other side by rotating the probe in the opposite direction as done previously, past the midsagittal plane until the second catheter comes into view. Push this in the same distance. Advance the catheters until they project well above the prostate, at least 3 cm. Push-and-pull the catheter in-and-out while observing it, to “free up” the prostate on the catheter so that it is not dragged too much in the cephalad direction by getting “stuck” on the catheter. Rotate the probe to visualise the other catheter, and repeat the process.
While placing these first catheters, ask the radiographers on the fluoroscope to obtain images of the catheter and to perfect the alignment. After the first catheters have been placed check them on the image-intensifier. In particular note the position of the tip in the bladder.
3.5.2 Anterior Catheters
Now you can proceed with the implant. The first two catheters have to some extent “fixed” the gland, so it will now be more stable. Now start from the most anterior catheters. This allows good visualisation of these catheters, since catheters placed posteriorly will tend to produce artefacts that will obscure the anterior parts of the prostate. Place two catheters simultaneously on the corresponding positions left and right, especially initially, to avoid pulling the gland to the left or right. As more catheters are placed this will be less of a problem. Recall the actual catheter position for the first two catheters compared with the intended position, as a guide to adjustments you might have to make, in order to position the catheters correctly. That is, if the first two catheters needed to be placed through the 3.5 row, to achieve a 3 row position in the gland on the projected grid, then if the most anterior aspect of the prostate has the 4 row of the grid projected over it, then in the first instance place the catheters through the 4.5 row holes in the template. Generally these will be placed at the c and d row on the projected template, but there might also be a left-right offset in a similar fashion to the anterior-posterior one mentioned and in this case these catheters might be at D and E, or at C and D.